In a triangle, we use terms like adjacent and opposite. These refer to sides in relation to angles. In our musical triangle, the drummer is at one angle in the back. This side, where the audience is, is called the opposite side.
Trunc is database function, try using round for numeric values, or change the Processing of Query to database.
Cosine (cos) function - Trigonometry. In a right triangle, the cosine of an angle is the length of the adjacent side divided by the length of the hypotenuse. Try this Drag any vertex of the triangle and see how the cosine of A and C are calculated.